Wall mold in a Forest Service residence.

Molds (sometimes called mildew) are forms of fungi that are found both indoors and outdoors all year round, everywhere on the planet. There are thousands of species of mold. All molds need moisture to grow, and most prefer warm temperatures. Mold may be white, orange, green, brown, black, or other colors. Sometimes mold can be detected by a musty odor. Molds reproduce by microscopic cells called "spores" that spread through the air and form new mold colonies when they find the right conditions. All of us are exposed to fungal spores daily in the air we breathe, both outside and inside. Very few of us are affected.

For a few people, too much exposure to mold may cause or worsen asthma or allergies. The most common symptoms are cough, congestion, runny nose, eye irritation, and aggravation of asthma. More serious health effects—such as fevers and breathing problems—can occur but are unusual. Most symptoms are temporary and disappear when the mold problem is corrected.

Rot caused by mold in a Civilian Conservation Corps-era Forest Service building.

When molds are present in large quantities, they may cause nuisance odors. Mold can damage building materials, finishes, and home furnishings. Some molds can cause structural damage to wood and other building components.

This section is under construction. Please check back later for more information. Meanwhile, check out the Washington Office Engineering FSWeb section on mold (Web site available only to FS and BLM employees) for some Web links that provide more information.